Williams AV FM 557-24 – FM+ Dual FM and Wi-Fi System, 24 Receivers

Product Overview

The Williams AV FM 557-24 is a dual FM and Wi-Fi assistive listening system for mid- to large-sized venues, delivering ADA-compliant hearing assistance to every seat without dedicated installation accessories you may already own. The package combines the FM+ T55 transmitter with 24 PPA R37N FM receivers, surround earphones, neckloops, and an ADA wall plaque. Listeners can use the supplied body-pack receivers or stream the same audio to their own smartphones over the venue Wi-Fi network, making this large-area assistive listening system a practical fit for auditoriums and houses of worship.

Product Description

The FM 557-24 centers on the FM+ T55 transmitter, which replaced the earlier T45 and added simultaneous Wi-Fi audio streaming alongside the proven 72 MHz-band FM broadcast — two delivery paths from one half-rack box. Program audio connects through a combination XLR/1/4-inch jack that accepts balanced or unbalanced mic or line-level signals with selectable phantom power, and DSP processing offers selectable compression and filtering to keep speech intelligible. The 3.12-inch OLED display walks operators through configuration, while the hosted web page and Telnet-over-Ethernet support allow remote monitoring and integration with room control systems. Each of the 24 PPA R37N receivers selects among 17 wideband channels between 72.1 and 75.9 MHz with a simple seek button, runs approximately 50 hours on the included AA alkaline batteries, and is covered by a Lifetime PLUS limited warranty. Twenty-four EAR 022 surround earphones and six NKL 001 neckloops accommodate both conventional listeners and hearing aid users with telecoils, and the FM broadcast itself supports an unlimited audience, so the system scales as attendance grows. This base package omits the antenna, chargers, and rack kit; venues that want a turnkey rack installation should consider the FM 557-24 PRO package with charging and mounting hardware included. Additional receivers, antennas, and accessories are available in the Williams AV collection. Note that the FCC requires professional installation with an approved FCC 15.203-compliant antenna, and Wi-Fi streaming relies on the venue's existing wireless network.

Key Features

• Two Listening Paths, One Transmitter — The FM+ T55 broadcasts to dedicated FM receivers and streams over venue Wi-Fi to smartphones simultaneously.
• 24 Body-Pack Receivers — The included PPA R37N receivers with EAR 022 surround earphones satisfy ADA receiver-count requirements for large assembly venues.
• 17 Wideband Channels — Seek-button channel selection across 72.1–75.9 MHz allows interference-free operation alongside other systems in the facility.
• Long Battery Runtime — Each receiver operates roughly 50 hours on two AA alkaline batteries, which are included with the package.
• Telecoil Neckloops Included — Six NKL 001 neckloops deliver audio directly to telecoil-equipped hearing aids and cochlear implants.
• DSP Audio Processing — Selectable compression and high-pass/low-pass filtering optimize the broadcast for speech intelligibility.
• Network Management — A hosted web interface and Telnet control over Ethernet support remote configuration and third-party control integration.
• Unlimited Listener Capacity — The FM broadcast serves any number of receivers, so the system expands without replacing the transmitter.
• ADA Signage Included — The IDP 008 wall plaque notifies visitors that hearing assistance is available, supporting 2010 ADA guideline compliance.

Typical Applications

• Auditorium
• House of worship
• Government space
• Multi-purpose room
• All-hands room
• Commercial meeting space

Technical Specifications

Frequently Asked Questions

What is the difference between the FM 557-24 and the FM 557-24 PRO?

Both packages share the same T55 transmitter and 24 R37N receivers. The PRO adds installation accessories — a remote coaxial antenna, rack panel kit, two 12-bay chargers, and NiMH rechargeable batteries — while this base package ships with alkaline batteries and no antenna or rack hardware.

Do I need to buy an antenna?

An FCC 15.203-compliant antenna such as the ANT 005, ANT 021, ANT 024, or ANT 025 is required and is not included in this package. The FCC also requires professional installation; consult the Williams AV Antenna Selection Install Guide.

Can attendees listen on their phones?

Yes. Once the transmitter is connected to the venue's Wi-Fi network, listeners can stream the audio to their smartphones, supplementing the 24 hardware receivers at no additional per-listener cost.

How do the neckloops support hearing aid users?

The NKL 001 neckloops plug into the R37N receiver and induce the audio signal magnetically into any hearing aid or cochlear implant with a telecoil, providing direct, clear coupling without earphones.

Is the receiver count expandable?

Yes. The FM broadcast supports an unlimited number of listeners, so additional PPA R37N receivers can be added at any time without changes to the transmitter.

What warranty coverage applies?

The transmitter carries a two-year parts and labor warranty; each R37N receiver is backed by a Lifetime PLUS limited warranty, excluding earphones, headphones, and batteries.